Fuel pump



Jap. 21, i y H; RMILLER l FUEL PUMP Filed Nov. 5, 194s au j ww INVENTOR Horace P VPatented Jan.

- 'UNH-n am j FUELrUMP v i HoraceP. Miller, OaklandJ Calif.

Application November` 5, 1943, SerialnNo. 50il,10 v s claims. (ol. s-37) My invention relates to pumps and particularly tohigh pressure fuel pumps. 4

Among the objects of my invention is the pro- Vvision of a high pressure pump with accurately -timed delivery, and capable of being4 operated at very high speeds. Another object is the provision of a high pressure pump in which the pressure on the fuel remains .constant at a predetermined amount. Still another .object is the provision of a fuel pump of the character described in which there 'are no ball check or poppet-vvalves;

My invention possesses other objects and features of value, some of which, with the foregoing, will be set forth in the following description of the invention. It is to be understood :that I do not limit myself to the showing made by the said description and the drawing, as I .may adopt variant forms of the invention within the scope'oi the appended claims.

-Referring to the drawing: Figure 1 is a vertical' sectional view of a pump embodying my inven` thickened upper wall I3 tion. The plane of .section is'indicated by .the l line I-I of Figure 2. Figure 2 is a side elevation of a four-unit pump.

In terms of broad inclusion each unit of my pump comprises a cylinder in one end of which a plunger is reciprocated by suitable connection to a power driven shait` 'In the other end of the 'cylinder, a second plunger is pressed by an adinstable tension spring, and .the penetration of the second plunger into the'cylinder is controlled by an adjustable stop. By regulation of .the

spring tension the pressure on the fuel oil delivered by the pump is controlled; and by regulation of the adjustable stop, the quantity of fuel oil delivered with each pressure stroke of .the power driven or pressure plunger., is controlled.

The inner end of the pressure plunger is prei'- erably recessed to provide a passage opening on the inner end of the plunger and also on its side;

and the arrangement and proportion of parts is preferably such that when the plunger ls at the low point of its stroke, fuel oil flows into the passage from an aligned feed port or passage inthe wall of the lcylinder .and into the space between the ends 'of the two plungers, filling both space and passage.

At the top of its stroke thev passage in the. side of .the plungeris `in register with a fuel delivery port or passage at which time the oil caught between the two plungers is forced through the passage by the spring pressure on the second plunger. Because the entire periphery of the plungers seals off the feed-and delivery ports, the parts do not require so close or accurate a fitting as in other by drilling a "typesfof pressure pumps; and the ating life of the mechanism without attention 'is ligure being in its low engine, the spacing between the eccentrics would be 60. l

almost limitless.

yIn greater detail,A my invention as embodied in the structure shown in the accompanying drawing comprises a housing conveniently .made in three parts-fa cylinder block 2in which four-cylindrical bores 3 are formed, a crank case 4, in

which is arranged the driving mechanism, includ-` ing the driving shaft 8, preferably connected through the usual means .to the engine shaft,

and a hood l closing inthe top.l The three parts. assemblyof four form a small, compact, closed pump units, held together by screws 8.

Slidably disposed in thelower half ofeach cyl-'- inder is a piston, preferably a plunger 9, conveniently called a pressure plunger, and having a head I Il at its lower end; engaged in a`T-slot inblock YIl which is Slidthe cylindrical cross-.head able in a cylindrical slideway I2, formed in the ofthe crank case 4. The lower end of the cross-head is slotted and a pivot pin I6 pivotally connects .the cross-head tol an eccentric I1l mounted on the eccentric disk I8, ilxed on the drive shaft 6, The lower part of the eccentric extends into a body in the bottom of the case. The lubricant is introduced into the case, and checked through an openj cover ing normally closed by the plug 2|, in the plate 22, forming a removable side wall 'for convenience 1n assembly of the four eccentrica and connected parts. In Figure 2, the four eccentricA i disks I 8 are shown in dotted lines at low, high and intermediate apart', and the rst one at the leit oi' the position. .In a .6 cylinder of each pressure plunger 9 is formed with a passage opening on the end and on the side. Conveniently the passage is made hole 26 axially in the end ol' the plunger to meet two transversely extending holes 21 at their intersection in the center 'of the The upper end plunger. The transverse holes at their outer ends terminate in the peripheral groove 28, so that there is a continuous passage, opening around the entire plunger side and on the end of `the plunger. The parts are spaced and proportioned so that when the plunger is at the bottom of its stroke, as shown in Figure l, the side opening 28 of the passage registers with a feed or' delivery port 29, connecting .the fuel supply passage 3| with the interior wall or face of the cylinder bore. This fuel supply passage 3i exefficiente-per- I 9 of lubricant lying posi-tions, the four being spaced' i tends" through the body' of the cyunder broek and of thepump units, either supplies fuel to4 each a' gear pump interposed by gravity feed or by ,in the line.

The period of registrationl of the feed port and side opening of the passage is of course very brief, but in that instant, fuel from the supply passage flows through the plunger and out at the top end into whatever space 32 exists above the pressure plunger. This space or chamber 32 in the cylindrical bore immediately above the pressure plungergis the measure of the fuel charge to be forcibly be the exact amount forced out of the chamber 32 between vthe two plungers. It will also be clear that the cap38 may be lowered to its extreme position in which the lower end of the metering plunger will touch the upper end of 'the pressure plunger at its high point, so that the volume of chamber 32 approaches zero. Un-

' der these conditions, the fuel 'oil will' merely fill injected into the associated engine cylinder; and v respondingly determines the innermost position of the metering plunger and Athe size of the chamber 32. 'Means are provided for selective adjustmentof the'stop, so that the quantity of fuel injected into the engine cylinders may be controlled. v Formed on the outer cylindrical face of the cap are gear teeth Il, meshing with the teeth of the rack 42, arranged in a slideway formed in the hood 1, and connected to an operating or throttle-lever bysuitable'linkage 43. Movement of the lever is effective through the rack to turn the cap in or out to reduce or increase the minimum volume vof the chamber 32.

Means are provided for maintaining on the head-31 of themetering plunger, a substantially -constant but adjustable resilient pressure. This is accomplished by interposing between the head and the housing hood 1 a coil spring 41, seated aroundthe stud 48 on the head and on a similar stud and head 49 carried by the screw 5|, threaded into the top of the head 1, and held by the lock nut 52. Adjustment of the screw in or out will of course vary the tension on the spring,

Formed in theI cylinder block, preferably on the opposite side of each bore from the feed port is a fuel delivery passage 53, opening in a delivery port inthe wall of the bore a short distance above the feed port.- The delivery passage 'terminates atfthe outside of the cylinder block in a -threaded aperture. in which the delivery pipe 54 leading to the engine cylinder is removably held. The spacing of the parts isfsuch that the side opening 28 of the pressure plunger passage registers with the'delivery port and passage 53 when the-pressure plunger is at the top of its stroke.` r

With the chamber 32 filled with fuel, upward movement of the pressure plunger compresses the fuel against the metering plunger which then rises against the pressure of the spring 41, so that when the pressure plunger reaches the top of its stroke and the passage 28registers with the delivery port,'the oil in the chamber 32, under the force applied by the compressed spring, flows back through the passages 26-21-28 and 53- into the pipe 54 and thence to the engine cylinder.

It will bev readily understood that while the several passages will remain full of oil after the operation has once been started, the amount of fuel oil injected into the engine cylinder will a nipple 39, surrounding thev the upper portion of each cap-stop obviously raises or lowers it and corthe plunger passages, but none will be injected into the delivery passage. At the other extreme of movement of the stop, the separation between the vplunger ends, that is, the volume of chamber 32 is at the maximum and the maximum charge of ,fuel oil is injected. In all positions however between` these extremes the pressure of the spring as adjusted by the set screw 5I is substantially'the same, and the oil isini jectedunder substantially constant pressure irrespective of the quantity handled, or variation in speed of the drive shaft B and pressure plungers. i

An important feature of my invention is the fact that thoroughly eflicient performance over a very long operating life'is secured with oper-H ating parts, in themanufacture of which conv sidera-bly. wider tolerances are permitted-than would normally obtain in mechanisms of this sort. A considerable amount of leakage 4past the plungers is expected and has to be taken careof. Thisv is most easily done by providing a drain passage 6I, extending from the 'upper face of the cylinder block under the cap intoa recess f 62, surrounding the pressure plunger on the un-Y derside of the block. A passageI 63 connects thisk v recess to the fuel tank. -Both plungers of each,-

pump unit, the cap-stops, the'rack and crossheads are lubricated by thisffuel oil leakage.

Iclaim: 1. A fuel injection device comprising a cylinder, a pressure plunger in the cylinder, means for reciprocating the plunger through pressure and recovery strokes, a fuel passage-in the plunger opening on its inner end and upon the side thereof in aligned feed and delivery ports, a fuel feed passage opening into the cylinder in registerri/ith the feed port of said plunger passage i when the plunger is at the end of its recovery stroke, a fuel delivery passage opening into the cylinder in register with the delivery port of said plunger'passage when the plunger is at the end of its pressure stroken-.metering plunger slidable in the cylinder, resilient means for pressing the metering plunger into the cylinder, and

means for varying the inward limit'of movement of the metering plunger.

2. A'fuel injection devicecomprising arcylin- A der, a pressure plunger in the cylinder, means forv 1 reciprocating the plunger through pressure and recovery strokes', a fuel passage in the plunger opening on its inner endV and upon' the side thereof in aligned feed andy delivery ports, a fuel feed passage opening into the cylinder in register with the feed port of said plungerpassage when the plunger is at the end ofits recovery stroke, a fuel delivery passage opening into the cylinder in register with the delivery-port of said plunger passage when the plunger'is at the end of its pressure stroke, a metering plungerA lslidable in the cylinder, resilient means' for pressing the metering plunger'into the cylinder, a stop for limiting the inward movementof-themetering plunger, and means for varying the position of the stop.

3. A fuel injection device comprising a cylinder, i a pressure plunger in the cylinder, means for resage when the plunger is at the end of its pres# sure stroke, a metering plunger slidable in the cylinder. resilient means for pressing the metering plunger into the cylinder, a cap threaded on Ythe cylinder and forming a stop for limiting the `inward movement o1' the metering plunger, and

means for rotating the cap to vary the position of the stop.

HORACE P. MILLER. 

